google/gemini-4-carbonGemini 4 Carbon is Google's most capable reasoning model, built for sustained agentic coding, complex software engineering, multimodal knowledge work, scientific reasoning and cybersecurity defense. It spends more thinking tokens per turn than Gemini 4 Argon to explore and verify its work on hard problems. It accepts text, images, video, audio and PDFs and returns text, with a unified 1,048,576-token input and output window, tunable thinking levels (low, medium, high; default medium), and long decode past 64K tokens, up to 1M, using background execution. It supports tool calling, structured outputs, code execution, computer use, file search, URL context, Google Search and Maps grounding, and implicit context caching. It is not available on the Gemini API free tier.